Comet Halley (1P/Halley)

Discovered by:          Prehistoric, Edmond Halley first recognised the periodicity
Discovery date:         Prehistoric       
Peak magnitude:      +2.4 (1986 return)
Aphelion:                  35.08 AU (5.248 billion kilometres or 3.261 billion miles)
Perihelion:                0.5860 AU (87.66 million kilometres or 54.83 million miles)
Semi-major axis:       17.83 AU (2.667 billion kilometres or 1.657 billion miles)
Eccentricity:              0.9671
Orbital period:            75.32 years
Inclination:                162.3 degrees

Last perihelion:          February 9th, 1986
Next perihelion:         July 28th, 2061

Halley's Comet (ESA)

Comet Halley or Halley's Comet is the best known and most famous comet of all.

It's a short period comet that's visible from Earth every 75–76 years and has been observed by astronomers since at least 240 BC.

In 1066, Halley's appearance was recorded on the Bayeux Tapestry.

Usually comets are named after the person or persons who discovered them. Halley (along with a few other comets) is different in that it was named after the person who first computed its orbit; English astronomer Edmond Halley in 1705.

Before this, the comet was recorded many times by Chinese, Babylonian, and medieval Europeans, but never recognised as being the same object.

Holds the distinction of being the only naked-eye comet that can be seen twice in a human lifetime.

Was first photographed and spectroscopic data obtained during the 1910 approach. On this occasion the comet passed close to Earth and was a spectacular sight; the Earth even passing through part of the comet tail.

Last appearance was in 1986 when Halley was best seen from the Southern Hemisphere. Sadly, the apparition was a poor one; Halley was on the opposite side of the Sun to the Earth and although visible to the naked-eye it reached at best only 2nd magnitude.

An armada of spacecraft visited Halley in 1986, including the Giotto and Vega missions that gave planetary scientists their first view of its surface and structure.

Nucleus of Halley's Comet (Halley Multicolor Camera Team, Giotto Project, ESA)

The comet nucleus is irregular, measuring about 15 x 8 x 8 kilometers (9.4 x 5 x 5 miles).

About 25% of the nucleus has been imaged by spacecraft flybys, revealing an extremely varied surface with hills, mountains, ridges, depressions and at least one crater.

Will next return in 2061.

Of all periodic comets, this one is the most active.

Halley's Comet is the parent body of two annual meteor showers, the Eta Aquariids (in May) and the richer Orionids (in October).